handler/mac: Log a warning when an exception message has a suspicious

util/mach/exception_ports_test.cc

Index: util/mach/exception_ports_test.cc
diff --git a/util/mach/exception_ports_test.cc b/util/mach/exception_ports_test.cc
index 8948eae791668123ced9510c5a824d1f09d91a26..8122906090dbbf173d706c4baa4ac83e4a20eff3 100644
--- a/util/mach/exception_ports_test.cc
+++ b/util/mach/exception_ports_test.cc
@@ -197,6 +197,8 @@ class TestExceptionPorts : public MachMultiprocess,
       SetExpectedChildTermination(kTerminationSignal, signal);
     }
 
+    EXPECT_EQ(0, AuditPIDFromMachMessageTrailer(trailer));
+
     return ExcServerSuccessfulReturnValue(behavior, false);
   }
 
@@ -440,13 +442,14 @@ class TestExceptionPorts : public MachMultiprocess,
       UniversalMachExcServer universal_mach_exc_server(this);
 
       const mach_msg_timeout_t kTimeoutMs = 50;
-      kern_return_t kr =
-          MachMessageServer::Run(&universal_mach_exc_server,
-                                 local_port,
-                                 MACH_MSG_OPTION_NONE,
-                                 MachMessageServer::kOneShot,
-                                 MachMessageServer::kReceiveLargeError,
-                                 kTimeoutMs);
+      kern_return_t kr = MachMessageServer::Run(
+          &universal_mach_exc_server,
+          local_port,
+          MACH_RCV_TRAILER_TYPE(MACH_MSG_TRAILER_FORMAT_0) |
+              MACH_RCV_TRAILER_ELEMENTS(MACH_RCV_TRAILER_AUDIT),
+          MachMessageServer::kOneShot,
+          MachMessageServer::kReceiveLargeError,
+          kTimeoutMs);
       EXPECT_EQ(KERN_SUCCESS, kr)
           << MachErrorMessage(kr, "MachMessageServer::Run");